Fix inverted index duplicate creation issue

- Add table existence check before creating indexes
- Improve error handling for ClickZetta specific error messages
- Remove duplicate _table_exists method definition
- Prevent high-frequency index creation attempts during bulk operations

This fixes the "already has index with the same type" errors during
large knowledge base construction with 600+ documents.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

api/core/rag/datasource/vdb/clickzetta/clickzetta_vector.py

@@ -172,6 +172,11 @@ class ClickzettaVector(BaseVector):
     
     def _create_table_and_indexes(self, embeddings: list[list[float]]):
         """Create table and indexes (executed in write worker thread)."""
+        # Check if table already exists to avoid unnecessary index creation
+        if self._table_exists():
+            logger.info(f"Table {self._config.schema}.{self._table_name} already exists, skipping creation")
+            return
+            
         # Create table with vector and metadata columns
         dimension = len(embeddings[0]) if embeddings else 768
 
@@ -187,6 +192,7 @@ class ClickzettaVector(BaseVector):
 
         with self._connection.cursor() as cursor:
             cursor.execute(create_table_sql)
+            logger.info(f"Created table {self._config.schema}.{self._table_name}")
 
             # Create vector index
             self._create_vector_index(cursor)
@@ -245,9 +251,12 @@ class ClickzettaVector(BaseVector):
             cursor.execute(f"SHOW INDEX FROM {self._config.schema}.{self._table_name}")
             existing_indexes = cursor.fetchall()
             for idx in existing_indexes:
-                # Check if inverted index already exists on the content column
-                if Field.CONTENT_KEY.value in str(idx).lower() and "inverted" in str(idx).lower():
-                    logger.info(f"Inverted index already exists on column {Field.CONTENT_KEY.value}")
+                idx_str = str(idx).lower()
+                # More precise check: look for inverted index specifically on the content column
+                if ("inverted" in idx_str and 
+                    Field.CONTENT_KEY.value.lower() in idx_str and
+                    (index_name.lower() in idx_str or f"idx_{self._table_name}_text" in idx_str)):
+                    logger.info(f"Inverted index already exists on column {Field.CONTENT_KEY.value}: {idx}")
                     return
         except Exception as e:
             logger.warning(f"Failed to check existing indexes: {e}")
@@ -265,19 +274,27 @@ class ClickzettaVector(BaseVector):
             logger.info(f"Created inverted index: {index_name}")
         except Exception as e:
             error_msg = str(e).lower()
-            if ("already exists" in error_msg or 
+            # Handle ClickZetta specific error messages
+            if (("already exists" in error_msg or 
                 "already has index" in error_msg or 
-                "with the same type" in error_msg):
+                "with the same type" in error_msg or
+                "cannot create inverted index" in error_msg) and
+                "already has index" in error_msg):
                 logger.info(f"Inverted index already exists on column {Field.CONTENT_KEY.value}")
+                # Try to get the existing index name for logging
+                try:
+                    cursor.execute(f"SHOW INDEX FROM {self._config.schema}.{self._table_name}")
+                    existing_indexes = cursor.fetchall()
+                    for idx in existing_indexes:
+                        if "inverted" in str(idx).lower() and Field.CONTENT_KEY.value.lower() in str(idx).lower():
+                            logger.info(f"Found existing inverted index: {idx}")
+                            break
+                except Exception:
+                    pass
             else:
                 logger.warning(f"Failed to create inverted index: {e}")
                 # Continue without inverted index - full-text search will fall back to LIKE
 
-    def _table_exists(self) -> bool:
-        """Check if the table exists."""
-        with self._connection.cursor() as cursor:
-            cursor.execute(f"SHOW TABLES IN {self._config.schema} LIKE '{self._table_name}'")
-            return len(cursor.fetchall()) > 0
 
     def add_texts(self, documents: list[Document], embeddings: list[list[float]], **kwargs):
         """Add documents with embeddings to the collection."""